Lennox VOSA036S4 User manual

1
©2017 Lennox Industries Inc.
Dallas, Texas, USA
INSTALLATION
INSTRUCTION
VRF SYSTEMS -- Indoor Units
507447-01
03/2017
THIS MANUAL MUST BE LEFT WITH THE OWNER
FOR FUTURE REFERENCE
Shipping and Packing List
General
The VOSA dedicated outdoor air concealed ducted
indoor units are matched with an outdoor heat pump
unit (excluding Mini-VRF) to create a VRF (variable
refrigerant flow) system that uses HFC-410A refrigerant.
Refer to the Product Specification bulletin (EHB) for
the proper use of these indoor units with specific heat
pumps, heat recovery units, mode switching devices,
branch pipes, line sets and controls.
VOSA Outdoor Air Units
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
Check the components for shipping damage. If you find
any damage, immediately contact the last carrier.
Package 1 of 1 contains the following:
1 - Assembled dedicated outdoor air concealed ducted
unit
Refrigerant piping insulation sleeves
2 - VOSA036 and VOSA048
4 - VOSA054 and VOSA072
1 - Flexible condensate connector (VOSA036-048)
1 - Hose clamp (VOSA036-048)
1 - Condensate connection pipe (VOSA054-072)
1 - Roll tape for condensate pipe (VOSA054-072)
1 - Branch pipe kit (VOSA054-096)
Flare Nuts
1 - VOSA036-048
2 - VOSA054-096
2 - Connector for electronic expansion valves and liquid
lines (VOSA054-072)
1 - Resistor
1 - Installation manual
WARNING
Improper installation, adjustment, alteration, ser-
vice or maintenance can cause property damage,
personal injury or loss of life.
Installation and service must be performed by a li-
censed professional HVAC installer, service agency
or the gas supplier.
Failure to follow safety warnings and these instruc-
tions exactly could result in property damage, dan-
gerous operation, serious injury, or death.
Any additions, changes, or conversions required in
order for the appliance to satisfactorily meet the ap-
plication needs must be made by a licensed profes-
sional HVAC installer (or equivalent) using factory-
specified parts.
Do not use this system if any part has been under
water. A flood-damaged appliance is extremely dan-
gerous. Immediately call a licensed professional
HVAC service technician (or equivalent) to inspect
the system and to replace all controls and electrical
parts that have been wet, or to replace the system, if
deemed necessary.
The State of California has determined that this
product may contain or produce a chemical or
chemicals, in very low doses, which may cause
serious illness or death. It may also cause cancer,
birth defects, or reproductive harm.
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
IMPORTANT
The Clean Air Act of 1990 bans the intentional venting
of refrigerant (CFC’s and HCFC’s) as of July 1, 1992.
Approved methods of recovery, recycling or reclaiming
must be followed. Fines and/or incarceration may be
levied for non-compliance.
NOTE - VOSA054 and VOSA072 units have special
wiring and piping considerations, see page 17.

2
Model Number Identification
Safety Requirements
ELECTRICAL SHOCK, FIRE, OR EXPLOSION HAZARD.
Do not touch the unit or the controller if your hands are wet.
DO NOT spray water on the indoor unit for any reason.
Do not replace a fuse with a fuse of a different rating. Do not use a jumper wire to replace a fuse. Do not insert
your hands, tools or any other item into the air intake or air outlet at either the indoor or outdoor unit.
Do not allow children to operate the system.
WARNING
!
V OS A 036 S 4 - 1 P
Brand/Family
V = Variable Refrigerant Flow (VRF)
Major Design Sequence
A = 1st Generation
Cooling Efficiency
S = Standard Efficiency
Refrigerant Type
4 = R-410A
Minor Design Sequence
1 = 1st Revision
2 = 2nd Revision
3 = 3rd Revision
Voltage
P = 208/230V-1 phase-60hz
Nominal Cooling Capacity - Btuh
036 = 36,000 Btuh
048 = 48,000 Btuh
054 = 54,000 Btuh
072 = 72,000 Btuh
System Piping
CAUTION
VRF system piping is customized for each installation.
The LVSS piping report is an engineered design that
must be followed. The piping diagram or diagrams
included within the LVSS report have been prepared
based on the information provided to the Lennox VRF
applications department.
When the indicated lengths change from the figures
stated within the report, it is imperative that prior to the
commencement of the refrigerant pipe work installation,
Lennox VRF applications department are informed of
these proposed changes.
Upon receipt of this new information the Lennox VRF
applications department will confirm any changes that
may be applicable to this installation. If changes are
required, a new piping diagram will be produced and will
supersede all other previously provided documents.
Failure to provide this information regarding changes
to the original design may lead to insufficient capacity,
equipment failure, warranty being made void and the
refusal to commission the system.
Unit Type
OS = Dedicated Outdoor Air Concealed Ducted Indoor Models

3
Unit Dimensions - Inches (mm)
VOSA036S4, VOSA048S4
AIRRETURN
AIRSUPPLY
LIQUID
PIPE
GAS
PIPE
RETURN AIR VIEW
TOP VIEW
SUPPLY AIR VIEW
HOLES FOR SUSPENDING (4)
42-1/4 (1073)
(Duct Opening)
45-1/4 (1149)
13-3/8 (339)
(Duct Opening)
2-1/2
(65)
3-1/4
(83) 1-1/4
(38)
3-1/4
(83)
2 (51)
SUPPLY AIR
DUCT FLANGE
1-3/8
(35)
10 (253)
3/4 (19)
RETURN AIR
DUCT FLANGE
25-1/8
(638)
23-5/8
(600)
3-1/2
(89)
2-3/4
(70)
5-3/8 (137)
5/8 (16)
DRAIN
CONNECTION
(Either Side)
ELECTRICAL
CONTROL
BOX
51-1/4 (1302)
36-5/8 (930)
3-1/4
(83)
5-3/8
(109) 1-1/8 (29)
9-7/8 (251)
(Duct Opening)
3-1/2
(89)
16-1/2
(419)
10-5/8
(270)
2-1/4 (57)

4
LEFT SIDE VIEW RIGHT SIDE VIEW
ELECTRONIC
EXPANSION
VALVE
LIQUID
PIPE
GAS
PIPE
DRAIN
CONNECTION
(Either Side)
AUXILIARY
DRAIN
CONNECTION
(Either Side)
4-7/8 (124) 7-3/8 (187)
1-5/8
(41)
27-1/4
(692)
1-3/8
(35)
9-7/8
(251)
(Supply
Air Duct
Opening)
4-7/8
(124)
7-3/8 (187)
1-5/8 (41) 1/2 (11)
1/2
(11)
13-3/8
(339)
(Return
Air Duct
Opening)
2
(51)
VOSA036S4, VOSA048S4
16-1/2
(419)
ELECTRICAL
CONTROL
BOX

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Unit Dimensions - Inches (mm)
2-1/4 (57)
AIRRETURN
DRAIN
CONNECTION
AIRSUPPLY
SUPPLY AIR VIEW
TOP VIEW
RETURN AIR VIEW
VOSA054S4, VOSA072S4
44-1/8 (1121)
(Duct Opening)
3
(76)
13-1/2 (343)
(Duct Opening)
2-3/8 (60)
3-7/8 (98)
RETURN AIR
DUCT FLANGE
HOLES FOR
SUSPENDING (4)
ELECTRICAL
CONTROL
BOX
56-3/4 (1141)
SUPPLY AIR
DUCT FLANGE
50-1/4 (1276)
32
(813)
2-5/8 (67)
15 (381)
(Duct Opening)
2 (51)
37 (940)
(Duct Opening)
8 (203)
18-1/2
(470)
RIGHT SIDE VIEW
2-3/4
(70)
1-3/4 (44)
5 (127)
4
(102)
ELECTRONIC
EXPANSION
VALVES
GAS
PIPES (2)
LIQUID
PIPES (2)
LIQUID
PIPES (2)
GAS
PIPES (2)

6
Clearances
Refer to figure 1 for minimum clearance requirements.
20” (508 mm) Minimum Service Clearance
24” (610 mm)
Air
Flow
24” (610 mm)
Minimum
Service
Clearance
TOP VIEW
FRONT VIEW
1” (25 mm) Minimum Clearance
Ceiling
Wall
Wall
1” (25 mm) Minimum Clearance
CeilingSuspended
Minimum
Service
Clearance
Figure 1. Minimum Installation Clearances
NOTE - No part of the suspended ceiling, or other supports not directly associated with the indoor unit installation, can
be fixed to, or touch the indoor unit, in any form. Minimum clearances must be observed at all times.

7
Unit Placement
AVOID
Do not install the unit in the following locations:
• Areas exposed to petrochemicals or petrochemical
products
• Areas exposed to salt or other corrosive materials or
caustic gasses
• Areas exposed to extreme voltage variations (such as
factories
• Tightly enclosed areas that may impede service of the
unit
• Areas exposed to fossil fuels (such as oil or gas in
kitchens)
• Areas exposed to strong electromagnetic forces
• Areas exposed to acids or alkaline detergents (laundry
rooms)
DO:
• Locate the unit so that it is not exposed to direct
sunlight
• Ensure the structural ceiling can support the weight
of the unit.
• Select a location where condensate line will have the
shortest run to a suitable drain per local codes.
• Allow sufficient space around unit for proper operation
and maintenance
• Install unit a minimum of 3 feet away from any antenna,
power cord (line) radio, telephone, security system, or
intercom. Electrical interference and radio frequencies
from any of these sources may affect operation
CAUTION
Do not place items which may be damaged by water
under or around the indoor unit.
The unit should be installed at least 8 feet above the
floor (if possible) to ensure maximum performance
and comfort, when installed in the horizontal
position only.
WARNING
Use the provided and specified components when
installing equipment. Failure to do so may result
in unit falling, water leaking or electrical shocks,
causing personal injury or equipment or property
damage.
Check stability of wall, floor, or ceiling and unit
support. If support is not capable of carrying
weight of the unit, unit may fall causing personal
injury or equipment damage.
Consider the possibility of earthquakes in your
area when installing the equipment. If the unit is
not correctly secured, it may fall, causing personal
injury or equipment damage.
Safely dispose of packing materials, which include
nails, wood and other sharp objects, as well as
plastic wrapping. Children playing with plastic
wrap or bags risk the danger of suffocation.

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Installation
It is important to locate the unit where it can be accessed
for service in the future. Refer to unit dimensions on Page
3 for exact locations of suspension brackets, return air
and supply air openings.
1. Make sure that the structural ceiling or slab is able
to support the weight of the indoor unit. It may be
necessary to add extra support.
2. Install suspension rods in the structural
ceiling or concrete slab in a suitable location.
If the structural ceiling is constructed of concrete,
install anchors to accept four ⅜” threaded rods to
suspend the indoor unit. If the structural ceiling
includes wooden joists, use angle iron or Unistrut
channel fixed securely in place to accept the ⅜”
threaded rods. NOTE - Threaded rod (requirement
of Lennox warranty program) is the ONLY acceptable
method of suspending the unit; do not use chains or
straps. See figure 2.
3. Slide one nut and one washer onto each threaded rod.
Use electrical tape to keep the washer from failing off.
Position the nuts slightly above the final resting place
of the four suspension brackets. See figure 3.
Figure 2. Suspending Methods
ANGLE IRON
BOLTED IN
PLACE ACROSS
WOODEN JOISTS
WOODEN JOIST
Ǫ´7+5($'(D
ROD ANGLE IRON
ACROSS
WOODEN JOISTS
$1&+25
CONCRETE CEILING
USING ANCHORS
Ǫ´7+5($'(D
ROD
4. Use either a mechanical lifting device or a minimum
of two people to raise the unit and insert the threaded
rods into the suspension brackets on the cassette
base. Slide a washer and then a nut onto each rod
below each suspension bracket. Use the leveling nut
(beneath suspension bracket) to adjust the unit to the
correct height. Remove the electrical tape holding the
upper washers and nuts in place and tighten each
of the four nuts above the brackets down onto the
brackets. This will ensure that the unit remains level.
5. If necessary, install a field-provided isolation grommet
as shown in figure 4 to prevent transmission of
vibration from unit to structural ceiling.
6. If the unit is being installed in an application that includes
a sheet rock (plasterboard) ceiling, it is required that
an access panel be installed in a suitable location.
This will also allow access for future maintenance
(requirement of Lennox warranty program).
Access is required during the commissioning process
to test the condensate disposal system (See figures
10, 11 and 12), to check the electronic expansion
valve and associated flare nuts (See figure 5), and to
check the local disconnect.
7. The unit is factory-configured for the supply air to be
delivered from the front and the return air filter at the
rear of the unit.
INSTALLATION GUIDELINES
• Install a field-provided isolation grommet as shown in
figure 4 to prevent transmission of vibration from unit
to structural ceiling.
• Provide separate support for the weight of the duct
system. Duct system must not be supported by the
indoor unit.
• Use flexible joints (canvas) at the point where the duct
connects to the unit on both ends. Material must meet
all local and national code requirements.
• When unit is being installed in a location where even
the slightest noise would be a problem (meeting room
or other very quiet space), design duct system to
avoid transmission of vibration to the structure to the
extent possible.
LEVELING
NUT
Ǫ” THREADED
ROD
SUSPENSION
BRACKET
FIELD-PROVIDED
ISOLATION GROMMET
WASHER
INDOOR UNIT
LEVELING
NUT
Ǫ” THREADED
ROD
SUSPENSION
BRACKET
SUPPLY AIR
OPENING
FRONT VIEW
When unit is
level, tighten
nut to secure
position of
suspension
bracket on
rod.
Figure 3. Suspension Hardware
Figure 4. Isolation Grommet

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Refrigerant Piping Connections
Field piping consists of two copper lines connected to the
indoor unit. Table 1 lists the connection sizes at the indoor
unit. The connections are made using the provided brass
flare nuts at the end of the refrigerant piping connections.
Both lines must be individually insulated.
NOTE - Always slide a flare nut onto the field-provided
refrigerant piping before flaring the lines.
1. The seal on the unit refrigerant piping connections
should remain in place until the last possible moment.
This will prevent dust or water from getting into the
refrigerant piping before it is connected.
2. Slowly loosen one of the flare nuts to release the
factory nitrogen charge.
3. Remove the flare nuts and discard the seal from each
of the piping connections.
4. Slide the flare nuts onto the ends of the field-provided
refrigerant piping before using a suitable flaring tool to
flare the end of the copper pipe.
System Size
(Btuh) Liquid Line Vapor Line
36000
48000 3/8” 5/8”
54000
72000 3/8” (2) 5/8” (2)
Table 1. Refrigerant Piping Connections
5. Apply recommended HFC-410A refrigerant lubricant
to the outside of the field-provided flared line sets
(figure 5 -- A).
6. Align the union tube and flared refrigerant lines with
each other, then tighten the flare nuts lightly at first to
obtain a smooth match (figure 5 -- B).
Figure 5. Making Connections at Indoor Unit
(Male to Female Connection)
7. Once snug, continue another half-turn on each nut
which should create a leak-free joint. A torque wrench
may be used to tighten flare nuts using Table 2
recommendations. See figure 6. Do not over-tighten
a flared joint.
A
B
CANT ON THE OUTSIDE OF
THE FLARE
MALE FLARE
CONNECTION
TORQUE WRENCH
TO INDOOR
UNIT
TO OUTDOOR UNIT
BACKUP
WRENCH
Figure 6. Tighten Flare Nut
NOTE - See page 21 for additional piping instructions for
VOSA054 and 072 units.
WARNING
Refrigerant leaks are unlikely; however, if a
refrigerant leak occurs, open a door or windows to
dilute the refrigerant in the room. Turn off the unit
and all other appliances that may cause a spark.
Call a licensed professional HVAC technician (or
equivalent) to repair the leak.
Use only R410A refrigerant to charge this system.
Use of other refrigerant or gas will damage the
equipment.
Do not allow air or other contaminants to enter
system during installation of refrigerant piping.
Contaminants will result in lower system capacity
and abnormally high operating pressures and may
result in system failure or explosion.
Insulate all refrigerant piping.
Refrigerant pipes may be very hot during unit
operation. Do not allow contact between wiring and
bare copper pipes.
After refrigerant piping connections have been
completed, check the system for leaks per
commissioning instructions.
IMPORTANT
The compressor in this unit contains PVE
oil (Polyvinylether). PVE oil is formulated for
hydrofluorocarbon (HFC) refrigerants, such as R-
410a, which this system contains. While it may have
some miscibility properties with mineral-based oil
and POE oil (Polyolester), it is not recommended to
mix PVE oil with any other type of refrigerant oil.
IMPORTANT
Always use two wrenches when tightening flare
nuts to avoid twisting refrigerant piping. DO
NOT over-tighten flare nuts.

10
Outside
Diameter Recommended Torque No torque wrench available
Finger tighten and
use an appropriately
sized wrench to turn an
additional:
Inches U.S.
3/8” 26 ft.-lb. 1/2 turn
5/8” 48 ft.-lb. 1 full turn
Table 2. Flare Nut Torque Recommendations
Figure 7. Insulate Flared Connections
UNIT
BASE
INSULATE ALL FLARED CONNECTIONS
TO PREVENT CONDENSATION
8. Flared connections should always be accessible and
must be insulated to prevent condensation. See figure
7.
Figure 8. VOSA054/072 Refrigerant Connections
Incoming
liquid line
connection
Incoming
liquid line
connection
Incoming
suction line
connection
Incoming
suction line
connection
Connect
these two
pipes
Connect
these two
pipes
Figure 9. VOSA036/048 Refrigerant Connections
9. Locate the pre-formed copper connector pipes
provided in the bag assembly (VOSA054-072 only).
These pipes are used to connect the unit piping to the
electronic expansion valves. Remove the plastic seal
from each end of the pipe. See figure 8.
10. Apply a small amount of recommended HFC-410A
refrigerant lubricant to the outside of the flared ends
of the connector.
11. Immediately align the connector pipe with the identified
piping in figures 8 & 9. Hand-tighten the flare nuts at
first. Then, use two wrenches to continue to tighten
the nuts without twisting the pipes. See figure 6.
Torque requirements are given in table 2. Again, do
not over-tighten the flared joints.
12. After refrigerant piping has been installed and
checked for leaks, apply insulation over the connector
pipes and all flared connections.
Incoming
liquid line
connection
Incoming
suction line
connection